1. Field of the Invention
This invention relates to a process for preparing anionic resinous aqueous emulsions useful for the treatment of fiber-containing products.
2. Description of the Prior Art
It is well known that polyurethane resins have good elasticity, and they have heretofore been used widely in various fields as adhesives, binders for non-woven fabrics, resinous components for artificial leathers, and the like. In general, they are used in the form of organic solvent solutions.
Conventional fiber-treating agents such as softening agents, antistatic agents and resin processing agents are generally used in aqueous systems. Accordingly, when a polyurethane resin is used together with conventional fiber-treating agents, it is preferred that the resin be water-soluble or that it be in the form of an aqueous emulsion.
Although polyurethane resins possess excellent physical properties as elastomers, because they contain in the molecule many hydrogen groups of carboamides, they have a large intermolecular cohesive force and they are poorly soluble in non-polar solvents. Accordingly, it is very difficult to form aqueous emulsions of polyurethane resins.
There is known a method for preparing stable emulsions by reacting an isocyanate-terminated urethane prepolymer with an excess of a polyalkylene polyamine to form a polyurethane-urea-polyamine, and rendering anionic the amino groups in the thus-formed polyurethane-urea-polyamine. The thus-formed emulsion gives an excellent rubbery elasticity when dried, and it is effective as a binder for fibers, papers, leathers, woods and construction materials. However, it is insufficient in the softness which is a very important requirement for fiber-treating agents.